题解 | #汽水瓶#

import java.util.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNextInt()) {
            int num = in.nextInt();
            if (num == 0) {
                break;
            } else {
                System.out.println(getDrink(num));
            }
        }

    }
    public static int getDrink(int bottle) {
        if (bottle <= 1) {
            return 0;
        } 
        // 防止无限循环导致的内存溢出
        else if (bottle == 2) {
            return 1;
        } 
        else {
            return bottle / 3 + getDrink(bottle / 3 + bottle % 3);
        }

    }
}